WikiLeaks has called off an event Tuesday in London, in which founder Julian Assange was expected to release what he has called damaging information about Hillary Clinton. The briefing was to have taken place at Ecuador’s embassy in the UK. Security concerns forced its cancellation.

Assange has been promising to release more information WikiLeaks collected from the recent hack of the Democratic National Committee. A tweet from WikiLeaks says the press conference has been moved to Berlin.

Tomorrow's press conf in Berlin proceeds. London speech by Assange has been moved to Berlin due to specific information. #wikileaks10

A group of high-ranking House Democrats asked the FBI to investigate whether Donald Trump’s campaign had any “overt and covert” connection to cyberattacks believed to be conducted by Russian government hackers.

The letter from the top ranking Democrats on the Oversight, Judiciary, Foreign Affairs and Homeland Security committees follow a similar missive from Senate Minority Leader Harry Reid, who also asked the FBI to look into any possible link between the campaign and Russian meddling in the US election.

Democrats have been painting Trump as a friend of the Russian government, which has a tense working relationship with the US, for much of the campaign. The drumbeat intensified after the Democratic National Committee was hacked this spring and a trove of internal documents were leaked online. Cybersecurity experts nearly unanimously point to Russian military and intelligence community hackers as the source.

In their letter, Reps. Elijah Cummings, John Conyers, Eliot Engel, and Bennie Thompson write to FBI Director James Comey that Trump’s comments inviting Russia to access his opponent Hillary Clinton’s emails and reported links between his staff and Russia raise red flags.

“Serious questions have been raised about overt and covert actions by Trump campaign officials on behalf of Russian interests,” they wrote. “It is critical for the American public to know whether those actions may have directly caused or indirectly motivated attacks against Democratic institutions and our fundamental election process.”

The FBI would only confirm it received the letter and had no further comment.

The language in the letter was echoed in a similar letter from Reid dated August 27 but reported late Monday by The New York Times in which he raised concern that Russia was extensively hacking and meddling in the US election — while also raising fears that Trump’s campaign may have involvement.

“It has come to my attention that last week, video evidence came to light of an individual with long ties to Donald Trump and his top campaign aides claiming to be in communication with WikiLeaks,” Reid wrote.

Trump adviser Roger Stone told CSPAN’s “Newsmakers” last week that he communicated with WikiLeaks founder Julian Assange through an intermediary. WikiLeaks was the venue for the release of the thousands of DNC emails.

The House Democrats also mentioned Stone’s previous comments about WikiLeaks in their letter, as well as questioning the background of Trump adviser Carter Page, who has extensive dealings with Gazprom, a Russian state-run energy company that is closely tied to Russian President Vladimir Putin. The letter notes that Page has raised eyebrows with comments critical of US policy and praise of Moscow.

The Trump campaign called the letters a distraction.

“These flailing attacks are a desperate attempt by Hillary Clinton and her Washington allies to distract from weeks of damaging revelations that Clinton sold access to the State Department through the Clinton Foundation,” said Trump spokesman Jason Miller. “If Hillary’s insider friends wanted to send an effective communication to a federal agency, they should circulate a Dear Colleague demanding that the Department of Justice open up an investigation into the Clinton Foundation’s shady foreign contributions.”

In July, after suspected Russian hackers released then emails from the DNC, Trump himself invited criticism by saying he hoped Russia had possession of Clinton’s emails and that they’d release them. He later walked back the remarks as “sarcastic.”

Democrats have argued that Trump’s campaign is linked to Russia for months, based in part on favorable statements Trump has made about Putin. His former campaign chairman, Paul Manafort, also worked for a pro-Russian Ukrainian ex-president, drawing scrutiny.